1. Field of the Invention
The present invention relates to electrical connectors to which daughter boards are connected by rotating the daughter boards to a lock position parallel to the mother boards.
2. Description of the Related Art
There is a demand for electrical connectors which occupy small areas on mother boards and provide large areas on daughter boards to mount many IC components, etc. Also, there is a demand for a low-profile electrical connectors for miniaturization of equipment.
Electrical connectors to which daughter boards are inserted obliquely and rotated downwardly to a lock position parallel to mother boards have been used to minimize the areas occupied by the electrical connectors. The electrical connectors are secured to the mother boards by the surface mounting technique.
An electrical connector of this type has a base with a slot into which a daughter board is inserted, and a pair of lock mechanisms to lock opposite side edges of the daughter board. A plurality of contact elements are provided in the slot for contact with the pads of the daughter board. The lock mechanisms have a movable section with a hook portion and a fixed section to protect the movable section and hold the daughter board.
One of the ways that the area of the mother board occupied by the electrical connector is minimized is to minimize the area of the lock mechanisms. In order to achieve this object, the lock mechanisms have been made from metal because it withstands large stress with small footage area. However, it is difficult to integrate the metal lock mechanisms with the plastic base. In addition, the lack of accurate assembling gives rise to unstable contact between the electrical connector and the daughter board.
In another conventional model, a metal armor is added to the movable section. However, the armor added to the movable section increases the area of a mother board occupied by the movable section, reducing the mounting area.
In order to increase the area of a daughter board on which IC components, etc. are mounted, it is desirable to minimize the area occupied by the lock mechanism on the daughter board. One of the conventional lock mechanisms is molded integrally with the connector body of an electrical connector, but the fixed section is provided outside the movable section which holds the daughter board so that the lock mechanism occupies a large area on the daughter board.
In order to provide a low-profile electrical connector, it is necessary to reduce the height of contact elements. To meet the requirement, it is necessary to reduce the height of contact elements while keeping the resilience of the contact elements.
One of the types of contact element is the so-called "stamped terminal." The stamped terminal is made by only stamping a metal sheet. The stamped terminal has a fixing section exposed to the mother board so that no or few circuit patterns are provided on the exposed area. In addition, the exposed area is soldered to the mother board, the terminal is so rigid that the insertion and removal force of a daughter board is very high while the amount of movement of the terminal is small. Moreover, the tolerance in thickness of daughter boards is too small to make daughter boards.
In order to receive a daughter board, the lock mechanisms must be flexible and, especially, the movable section must be resilient to withstand the opening movement. The conventional lock mechanisms are frequently broken by excessive movement and, therefore, there is a demand for a more reliable lock mechanism.